I've been looking for a replacement saddle bag, then saw this, looks good to me, but I think you really need two bottle cages, might interest some?
You need to have a spare inner tube with you on your ride and most riders have a small bag under the saddle for tyre levers, a small multi-tool and those very important spare tubes. Under the saddle is a great place to store it, but it can look a little bulky, especially on a smaller frame. The Tubo bag fits neatly into your bottle cage making the bike look 'race ready'
Made from waterproof Cordura material